Aircraft networks reduce wiring and improve data movement efficiency but require provable Quality of Service (QoS) and qualities such as latency and jitter are bounded and as small as necessary for required aircraft performance. The two main methods using Ethernet for doing this are Aeronautical Radio, Incorporated (ARINC) standard 664 and Time Triggered Protocol (TTP)-Ethernet. ARINC 664 provides a profiled network approach that allocates bandwidth to all end nodes of the network. All end nodes are asynchronous from each other and broadcast their data across “virtual links” to all subscribers of those links. This creates large latencies and jitter and often requires data to be transmitted at twice the required rate to deal with Nyqiust sampling issues. TTP-Ethernet uses a Time Division Multiple Access (TDMA) approach that allocates time periods to all end nodes of the network. These members must be synchronous and makes scheduling difficult. Also, fault modes must be considered when trying to synchronize across network lanes.
In these systems, data producing nodes push their data on the network. That is, when a data producing node determines that is has data to transmit, it broadcasts the data onto the network. Data consuming nodes, in turn, listen to data from the network. Each consumer node sorts through the data packets it receives to look for relevant data. The producing nodes broadcast each piece of information only once, leaving it up to a consumer node to vigilantly listen to the network to collect any data it needs. A producer node determines what data is to be provided to the network, and when (for example, at a periodic rate or based on a timeslot schedule). The result is that some consumer nodes will receive information that they do not need, and must sort through irrelevant data to find the data that is relevant. In some occurrences, a producer node will transmit packets of data at times when no consuming node requires that particular data.
For example, ARINC 664 is an asynchronous network protocol that utilizes the data “Push”. An ARINC 664 packet may include values for 100 different variables in a single message. A consumer node receiving that package would pick through the message to determine if it contains any relevant data. The consumer node may end up needing values for only one or two of the variables, but it will need to look through the entire message to retrieve only those variables of interest. The existing approaches thus increase the necessary overhead at the consumer node as well as latency in supplying consuming nodes the data they need to perform their respective functions.
For the reasons stated above and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the specification there is a need in the art for improved methods to address data latency in avionics networks.